After the iPad has enrolled MDM via DEP, you can mark it as Shared iPad in order to use Managed Apple ID. 

  1. Check if the device has installed MDM/Remote Management via DEP

    Apple > DEP > DEP Device

  2. Set as Shared iPad

    Action > Set Shared iPad

  3. Wipe Device and re-enroll the device as Shared iPad

    Device > Device Management > Select the device with Shared iPad label > Advanced > Wipe Device